Android网络实例:HTTP之利用HttpURLConnection访问百度、获取网络图片

概述MianActivity.javapublicclassMainActivityextendsAppCompatActivity{ButtonvisitWebBtn=null;ButtondownImgBtn=null;TextViewshowTextView=null;ImageViewshowImageView=null;StringresultStr=“”;ProgressBarprogressBar=null;ViewGroup

MianActivity.java

public class MainActivity extends AppCompatActivity {
button visitWebBtn = null;
button downimgBtn = null;
TextVIEw showtextVIEw = null;
ImageVIEw showImageVIEw = null;
String resultStr = “”;
Progressbar progressbar = null;
VIEwGroup vIEwGroup = null;
@OverrIDe
protected voID onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentVIEw(R.layout.activity_main);
initUI();
visitWebBtn.setonClickListener(new VIEw.OnClickListener(){

        @OverrIDe        public voID onClick(VIEw v) {            // Todo auto-generated method stub            showImageVIEw.setVisibility(VIEw.GONE);            showtextVIEw.setVisibility(VIEw.VISIBLE);            Thread visitBaIDuThread = new Thread(new VisitWebRunnable());            visitBaIDuThread.start();            try {                visitBaIDuThread.join();                if(!resultStr.equals("")){                    showtextVIEw.setText(resultStr);                }            } catch (InterruptedException e) {                // Todo auto-generated catch block                e.printstacktrace();            }        }    });    downimgBtn.setonClickListener(new VIEw.OnClickListener() {        @OverrIDe        public voID onClick(VIEw v) {            // Todo auto-generated method stub            showImageVIEw.setVisibility(VIEw.VISIBLE);            showtextVIEw.setVisibility(VIEw.GONE);            String imgurl = "https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=112912491,3646496790&fm=26&gp=0.jpg";            new DownimgAsyncTask().execute(imgurl);        }    });}@OverrIDepublic boolean onCreateOptionsMenu(Menu menu) {    // Inflate the menu; this adds items to the action bar if it is present.   // getMenuInflater().inflate(R.menu.main, menu);    return true;}public voID initUI(){    showtextVIEw = (TextVIEw)findVIEwByID(R.ID.textvIEw_show);    showImageVIEw = (ImageVIEw)findVIEwByID(R.ID.imagvIEw_show);    downimgBtn = (button)findVIEwByID(R.ID.btn_download_img);    visitWebBtn = (button)findVIEwByID(R.ID.btn_visit_web);}/** * 获取指定URL的响应字符串 * @param urlString * @return */private String getURLResponse(String urlString){    httpURLConnection conn = null; //连接对象    inputStream is = null;    String resultData = "";    try {        URL url = new URL(urlString); //URL对象        conn = (httpURLConnection)url.openConnection(); //使用URL打开一个链接        conn.setDoinput(true); //允许输入流，即允许下载        conn.setDoOutput(true); //允许输出流，即允许上传        conn.setUseCaches(false); //不使用缓冲        conn.setRequestMethod("GET"); //使用get请求        is = conn.getinputStream();   //获取输入流，此时才真正建立链接        inputStreamReader isr = new inputStreamReader(is);        BufferedReader bufferReader = new BufferedReader(isr);        String inputline  = "";        while((inputline = bufferReader.readline()) != null){            resultData += inputline + "\n";        }    } catch (MalformedURLException e) {        // Todo auto-generated catch block        e.printstacktrace();    }catch (IOException e) {        // Todo auto-generated catch block        e.printstacktrace();    }finally{        if(is != null){            try {                is.close();            } catch (IOException e) {                // Todo auto-generated catch block                e.printstacktrace();            }        }        if(conn != null){            conn.disconnect();        }    }    return resultData;}/** * 从指定URL获取图片 * @param url * @return */private Bitmap getimageBitmap(String url){    URL imgurl = null;    Bitmap bitmap = null;    try {        imgurl = new URL(url);        httpURLConnection conn = (httpURLConnection)imgurl.openConnection();        conn.setDoinput(true);        conn.connect();        inputStream is = conn.getinputStream();        bitmap = BitmapFactory.decodeStream(is);        is.close();    } catch (MalformedURLException e) {        // Todo auto-generated catch block        e.printstacktrace();    }catch(IOException e){        e.printstacktrace();    }    return bitmap;}class VisitWebRunnable implements Runnable{    @OverrIDe    public voID run() {        // Todo auto-generated method stub        String data = getURLResponse("http://www.baIDu.com/");        resultStr = data;    }}class DownimgAsyncTask extends AsyncTask<String, VoID, Bitmap> {    @OverrIDe    protected voID onPreExecute() {        // Todo auto-generated method stub        super.onPreExecute();        showImageVIEw.setimageBitmap(null);        showProgressbar();//显示进度条提示框    }    @OverrIDe    protected Bitmap doInBackground(String... params) {        // Todo auto-generated method stub        Bitmap b = getimageBitmap(params[0]);        return b;    }    @OverrIDe    protected voID onPostExecute(Bitmap result) {        // Todo auto-generated method stub        super.onPostExecute(result);        if(result!=null){            dismissprogressbar();            showImageVIEw.setimageBitmap(result);        }    }}/** * 在母布局中间显示进度条 */private voID showProgressbar(){    progressbar = new Progressbar(this, null, androID.R.attr.progressbarStyleLarge);    relativeLayout.LayoutParams params = new relativeLayout.LayoutParams(VIEwGroup.LayoutParams.WRAP_CONTENT,            VIEwGroup.LayoutParams.WRAP_CONTENT);    params.addRule(relativeLayout.CENTER_IN_PARENT,  relativeLayout.TRUE);    progressbar.setVisibility(VIEw.VISIBLE);    Context context = getApplicationContext();    vIEwGroup = (VIEwGroup)findVIEwByID(R.ID.parent_vIEw);    //		MainActivity.this.addContentVIEw(progressbar, params);    vIEwGroup.addVIEw(progressbar, params);}/** * 隐藏进度条 */private voID dismissprogressbar(){    if(progressbar != null){        progressbar.setVisibility(VIEw.GONE);        vIEwGroup.removeVIEw(progressbar);        progressbar = null;    }}

}

activity_main.xml

    <FrameLayout        androID:layout_wIDth="match_parent"        androID:layout_height="match_parent" >        <TextVIEw            androID:ID="@+ID/textvIEw_show"            androID:layout_wIDth="wrap_content"            androID:layout_height="wrap_content"            androID:text="hello_world" />        <ImageVIEw            androID:ID="@+ID/imagvIEw_show"            androID:layout_wIDth="wrap_content"            androID:layout_height="wrap_content"            androID:layout_gravity="center" />    </FrameLayout>    <button        androID:ID="@+ID/btn_visit_web"        androID:layout_wIDth="wrap_content"        androID:layout_height="wrap_content"        androID:layout_alignParentBottom="true"        androID:layout_alignParentleft="true"        androID:text="访问百度" />    <button        androID:ID="@+ID/btn_download_img"        androID:layout_wIDth="wrap_content"        androID:layout_height="wrap_content"        androID:layout_alignParentBottom="true"        androID:layout_toRightOf="@ID/btn_visit_web"        androID:text="下载图片"/></relativeLayout>

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